Bipolar is also known as manic depression which involves mood disorders. The elevated moods, or mania, crazy/happy moods are usually followed by manic depressive moods. Bipolar moods switch from one intense mood to the exact opposite mood. Like going from the north pole to it's opposite, the south pole.
Bipolar is a very serious disorder, I can occur in any age groups. Its is when you can be very happy (manic) to very down a negative (depressed) and then maybe get angry. Sometimes when a person has a negative depressive moment they can tend to become very negative toward their situations and think of suicide aka suicidal depression. Sadly, such events had happened to my uncle at the age of 24 and his life had ended.